The effectivness norton security base on cloud

1. I just wonder about the effectiveness of Norton Security when the computer don't connect to the internet as stated in promotion that the virus definition now base on cloud until 80% of the database, for.i.e when my friend connect his usb flash to my computer on which not connect to the internet whether my Norton Security will effective to automatic scanning even not connected to the internet.

2. When I do on Demand Scanning the pop windows remain me that my computer didn't connect to the internet that could reduced the effectiveness of the scanning, please advice me that's is true?, if yes it's mean my Norton Security will be useless?

Please explain me.

Tks & B/regards,